<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<script type="text/javascript">
			function add(a,b)  
			{  
			    alert(a+b);  
			    console.log(this)
			}  
			function sub(a,b)  
			{  
			    alert(a-b); 
			    console.log(this)
			}  
			
			add.call(sub,3,1);
			//add.apply(sub,[3,1]);
		</script>
	</head>
	<body>
	</body>
</html>
